FORSYTH COUNTY, Ga. -- An armed man was shot and killed by officers outside the Forsyth County Courthouse Friday morning, authorities said. A sheriff's deputy was wounded in the gunfire.

Police identified the suspect as 48-year-old Dennis Ronald Marx, a gun trader. Investigators believe Marx had been planning the courthouse shooting for a long time.

Forsyth County Sheriff Duane Piper said the incident began at around 10 a.m., when Marx drove up onto the sidewalk in front of the courthouse and threw spike strips and explosives out the car window, then began shooting through the windshield with an assault rifle, striking a deputy below the right knee.

"It appeared that he was trying to actually drive through the front of the courthouse," Piper said.

Police returned fire, shooting Marx multiple times and killing him. The gunfire lasted approximately three minutes.

"He came with the specific purpose of killing as many people as he could," Piper said.

An armed man attempting to assault the Forsyth County Courthouse was shot and killed by officers Friday morning, authorities said. A sheriff's deputy was wounded in the gunfire.

The suspect was carrying several homemade hand grenades, smoke grenades, tear gas grenades, homemade explosive devices, tear gas, water, zip ties and several magazines of ammunition. He was wearing body armor and a gas mask, according to Piper. The sheriff said it appeared as if Marx intended to take hostages inside of the courtroom. The explosive devices were said to be "unsophisticated," according to Piper.

Georgia Bureau of Investigation officials continued to search Marx's vehicle late into Friday night.

Eight officers fired on Marx, most were armed with pistols, two had assault rifles, Piper said in an afternoon news conference. Marx also had explosives on his body, and his body was booby-trapped.

Piper said that authorities searched Marx's home Lakeside Trail near Bald Ridge Marina Road in Cumming on Friday afternoon. The house was not booby-trapped, but explosives were found at the home, Piper said.

Piper said that the home had been booby-trapped before. He said deputies had seen "pits with punji sticks" at the home before.

Investigators said that no notes were found in the home and the motive for Marx's actions has yet to be determined.

Dennis Marx, the suspect in the Forsyth County Courthouse shooting Forsyth County Sheriff's Office

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Ann Shafer, one of Marx's attorneys, told 11Alive News her client was arrested over a year ago on charges of possession of marijuana with intent to distribute and use of a firearm in the commission of a felony. He was scheduled to appear in court Friday morning to enter a plea, but did not show up.

Shafer left the courthouse after waiting for Marx for about 40 minutes; as she walked out, she heard gunshots and said she wondered whether her client was responsible.

She is the suspect's second attorney in this case; his first attorney is Manny Arora, a well-known criminal defense lawyer. Marx retained Arora and Shafer after his original attorney, Jim Hardy, was diagnosed with cancer.

Shafer described Marx as "slightly unstable" at times.

"I find people remarkable in their reactions to the legal business," Shafer said of her feelings upon learning her client was a suspect in the shooting. "I feel very lucky that I walked out the back of the courthouse instead of the front."

She added that she was very concerned for her safety, as she and Arora have had some unsettling interactions with Marx, and said the suspect made "veiled threats" against her.

Interview with shootinig suspect's former lawyer

Marx was no stranger to the Forsyth County Sheriff's Office. Piper said deputies have had many run-ins with him.

Marx had filed a federal civil suit against the Forsyth County Sheriff's Office, alleged that the sheriff's office had "engaged in a pattern or practice of excessive force in violation of the Constitution and federal law." Click here to see the lawsuit.

The deputy who was hurt in Friday's incident was taken to a nearby hospital with a gunshot wound just below the right knee. He suffered a fractured fibula and tibia, according to Piper, and was in surgery on Friday afternoon. The injuries do not appear to be life-threatening, according to Piper. Authorities identified him as James Daniel Rush, 46, of Cumming. He has been a deputy in Forsyth County since Feb. 1990.

James Daniel Rush was injured in the shooting at the Forsyth County Courthouse on June 6, 2014.(Photo: Forsyth County Sheriff's Office)

Adam, who works near the courthouse, filmed some footage of police officers running toward the scene. Several gunshots can be heard in the video:

Phone interview with viewer Adam, who caught gunfire on cell phone

Witness Oscar Grandos, who was in the courthouse during the incident, told 11Alive News he heard a series of gunshots and saw several police officers "carrying big guns" running outside. He said people inside the courthouse were moved to a nearby restaurant as police investigated the shooting.

As Marx had several explosives on his person, a bomb squad was called. Police expanded the crime scene as they brought in a robot to aid their search.

The area was secured approximately two hours later.

"We want to make sure citizens know that the area has been secured at this time," Piper said in a release. "There should be no further danger to the public."

Businesses near the courthouse were placed on lockdown as police investigate. At least one woman from a nearby business was transported to a nearby hospital with unknown injuries.

The Georgia Bureau of Investigation was called in to help Cumming Police and the Forsyth County Sheriff's Office investigate the shooting.

Forsyth County Sheriff Duane Piper gives an afternoon update on a shooting at the courthouse earlier on Friday.